There are plenty of new ideas happening on the Fediverse but without the advertising budget none of them are catching on. So, instead, you end up with "Twitter but not tied to just Twitter" and "Instagram but not just tied to Meta", because those are services people recognise. A good example of this may be https://joinmobilizon.org/en/, which I haven't heard of a non-Fediverse alternative for.
What doesn't help is that the Fediverse can't just design its own protocol and run with it, the whole point is for stuff to be federated. A minimal compatibility with platforms like Mastodon or another video platform is expected, and that makes developing these platforms just a tad more difficult.
This isn't exclusive to the Fediverse either. HN is a Reddit clone, which itself is a clone of every similar platform before it, going back all the way to NNTP and before; Facebook cloned Twitter into Threads, just about every messenger on my phone is just copies of copies, Google Docs is a worse copy of Microsoft Office, Bing is just Google with a theme, and so on.