Or it could mean that the beast that was,was not yet is as the angel said was at a later time after Revelation 17 to ascend out of the pit, and that the ten horns had not yet recieved an kingdom as yet as the angel said and so she isnt being carried by the beast of Daniel until then.
First of all, we know that 7 heads of the beast in Revelation 17 are the very same heads of the 4 beasts in Daniel 7.
-The First beast in Daniel 7 has a lions head which is also the first head of the beast in Reveation 17.
-The Second beast in Daniel 7 has a bears head which is also the second head of the beast in Revelation 17.
-The Third beast in Daniel 7 has 4 leopard heads which are also the third to sixth heads of the beast in Revelation 17.
-The Fourth beast in Daniel 7 "was diverse from all the beasts that were before it; and it had ten horns" which is also the seventh head of the beast in Revelation 17.
We also know that the First beast represents Nebuchadnezzar AND his kingdom Babylon. How do we know this? Compare Daniel 7:4 with Daniel 4:32-37
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Daniel 7:4:
"The first was like a lion, and had eagle's wings: I beheld till the wings thereof were plucked, and it was lifted up from the earth, and made stand upon the feet as a man, and a man's heart was given to it."
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Daniel 4:32-37:
32 And they shall drive thee from men, and thy dwelling shall be with the beasts of the field: they shall make thee to eat grass as oxen, and seven times shall pass over thee, until thou know that the most High ruleth in the kingdom of men, and giveth it to whomsoever he will.
33 The same hour was the thing fulfilled upon Nebuchadnezzar: and he was driven from men, and did eat grass as oxen, and his body was wet with the dew of heaven, till his hairs were grown like eagles' feathers, and his nails like birds' claws.
34 And at the end of the days I Nebuchadnezzar lifted up mine eyes unto heaven, and mine understanding returned unto me, and I blessed the most High, and I praised and honoured him that liveth for ever, whose dominion is an everlasting dominion, and his kingdom is from generation to generation:
35 And all the inhabitants of the earth are reputed as nothing: and he doeth according to his will in the army of heaven, and among the inhabitants of the earth: and none can stay his hand, or say unto him, What doest thou?
36 At the same time my reason returned unto me; and for the glory of my kingdom, mine honour and brightness returned unto me; and my counsellors and my lords sought unto me; and I was established in my kingdom, and excellent majesty was added unto me.
37 Now I Nebuchadnezzar praise and extol and honour the King of heaven, all whose works are truth, and his ways judgment: and those that walk in pride he is able to abase.
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Notice in Daniel 4:33 that Nebuchadnezzar's hairs were "grown like eagles' feathers" due to having become as a beast on all fours eating grass for a period of "seven times".
And notice how from Daniel 4:34 Nebuchadnezzar is given back his sanity after the "seven times" have expired, so that he is no longer on all fours but is, in a sense, "lifted up from the earth" so that he is able to "stand upon the feet as a man" once again. Essentially now being able to clean/tidy himself which would naturally include "plucking" the hairs of his which had "grown like eagles' feathers".
Notice also how in Daniel 4:34-37 we can see that "a man's heart" is given to Nebuchadnezzar after enduring life as a beast for a span of "seven times".
So, including what is written about the head of gold portion of the statue, we can confirm that the first of the four beasts (and the first head of the 7 headed beast of Revelation) is Babylon.
What else do we know about the 7 heads of the beast of Revelation in regards to what each represents?
Consider Revelation 17:10
Revelation 17:10
"And there are seven kings: five are fallen, and one is, and the other is not yet come; and when he cometh, he must continue a short space."
Notice that the angel says to John "and one is". And also that "five are fallen". So what can we conclude from that information? We can conclude that John is currently living during the reign of the Sixth head, because "five have fallen". Now, who is the world power during Johns lifetime? Well its Rome right? So then lets count the heads to see which of the four beasts the sixth head lands on:
Head 1 = lion
Head 2 = bear
Head 3 = Leopard 1
Head 4 = Leopard 2
Head 5 = Leopard 3
Head 6 = Leopard 4 <-----
So therefore we know that John is alive during the reign of the 4th Leopard head, which MUST be Rome. So what does that mean for the 3 previous Leopard heads? Well they are of the same Leopard Beast, so the Leopard must represent 4 eras of the Roman Empire in some form.
We also know that the 4th beast in Daniel 7, whos head also represents the 7th head of the beast in Revelation 17, is "diverse from all the beasts that were before it" as stated in Daniel 7:7 and that it "is not yet come" (from Johns perspective). So it becomes quite clear that the fourth beast of Daniel 7, (i.e 7th head of the Beast of Revelation 17) is Not Rome, as many others tend to believe. It is entirely "diverse from all the beasts that were before it". It is not part of the Leopard beast.
So therefore we can conclude that the beast of Revelation 17 spans from the time of Babylon until this present time, and not "at a later time after Revelation 17".
We also know that its the fourth beast (i.e 7th head in Revelation 17) that has the 10 horns as stated in Daniel 7:7. And we know that the 7th head of Revelation 17 was "not yet come" (from Johns perspective). It is a world power beyond Johns time. It is yet to come. But that in no way indicates that the woman riding the beast of Revelation 17 has not yet come. Because the whole purpose of showing her riding the beast with 7 heads in Revelation 17 (which represent the world powers spaning from Babylon until now) is to show that she has guided/controlled those world powers via the various forms of Babylonian religions that each world power has worshipped during their lifetimes. Much like a horse rider guides/controls his/her horse.