What is the purpose of the first 0x04 byte in all extended public and private keys (xpub xprv ypub yprv zpub zprv …)?

BIP32 specifies the 4-byte version.

mainnet: 0x0488B21E public, 0x0488ADE4 private; testnet: 0x043587CF public, 0x04358394 private

BIP49 has the following variants:

Extended public keys use 0x049d7cb2 to produce a "ypub" prefix, and private keys use 0x049d7878 to produce a "yprv" prefix. Testnet uses 0x044a5262 "upub" and 0x044a4e28 "uprv."

BIP84 has the following variants:

Extended public keys use 0x04b24746 to produce a "zpub" prefix, and private keys use 0x04b2430c to produce a "zprv" prefix. Testnet uses 0x045f1cf6 "vpub" and 0x045f18bc "vprv."

The first thing I noticed about all this is 0x04. Then I noticed that in the Bitcoin Core testing framework, this first byte is separated out and called a “version”.

Is this the same as the “version” specified by BIP32? (Although there is a difference of 1 vs. 4 bytes?) What other versions are there? 0x04?