Bitcoin is certainly unique in being the first cryptocurrency.

But other coins can have unique qualities that Bitcoin can never adopt.

One such quality is simplicity. Although Bitcoin may be far less complex than some other chain like Ethereum, it still contains a nontrivial amount of complexity in itself, as witnessed by
the over 10,000 lines of code in libbitcoin-consensus.
Learning all the consensus rules in detail is quite an challenge, one that not many people have undertaken.
A lot of complexity resides in its Bitcoin Script language, even though none of that is needed to support
the vast majority of transactions. Even things like multisig, atomic swaps, discreet log contracts, and bidirectional payment channels can be implemented with just Schnorr signatures and timelocks.
Consensus rules can only ever grow in complexity, since they must be used to verify the full transaction history.

Another such quality is fair distribution. While Bitcoin had a relatively fair one, with no premine, it still did not decentralize wealth as much as one might like. Or rather, as future generations might like, since each successive generation only gets to mine 1/32 time as much as the previous one.
Of course, the huge advantage given to early miners/adopters, and lack of dilution, is great for speculation. But perhaps less so for actual use as currency.

Only one cryptocurrency combines a unique focus on simplicity with a uniquely fair coin distribution of 1 coin per second forever.

It also happens to feature a unique spam resistance; only a few bytes of arbitrary data can be inscribed into the chain with each transaction.

Of course, its uniquely high dilution (in initial decades) also make it uniquely uninteresting for the readers in this forum, that are almost exclusively only interested in speculation.