Jesus did more than 1 baptism Himself. He baptized with the Spirit and with fire...Matthew 3:11. The one baptism isn't what you think. The passage in Ephesians 4 is more extensive than just verse 5. Verse 4 mentions the Spirit, verse 5 mentions Christ, and verse 6 mentions the Father. One Lord, one faith, one baptism all speak of our relationship to Christ...faith in the Lord. This is spoken of in Romans 4 that we are buried with Christ in baptism into death. This is the symbolism of water baptism. We go to our death when we go beneath the water and rise to newness of life in Christ when we come out. It is spiritual as well in that it is the Spirit who actually places us into Christ, but one baptism doesn't negate the different baptisms mentioned in scripture, but identifies the one in view in the passage.
There is only one baptism for the Church, the baptism with the Spirit. We don't need symbolism anymore, we have the reality.