I'm surprised that you don't put decentralization at the heart of cryptocurrency. Yes, cryptocurrency has crypto-based encryption at its core, but the original idea of cryptocurrency was that you don't need to trust your money to a third party. And the centralized system is in fact a third party. So you're wrong to say that cryptocurrency shouldn't have decentralization.
If decentralization is the heart of cryptocurrency, the coins listed on CMC or Coingecko might be around 10-50, not 2K. Because 95% coins are centralized and it shouldn't be included as a cryptocurrency, then why it's included?
I don't see any other trusted decentralized coins except Bitcoin, Monero, Litecoin and DAI. There's a decentralized coins, but the marketcap is small and has higher chance to suffer 51% attack.
I'm not saying centralized coins is good, but I just want to be fair.
Of course all coins on CMC are cryptocurrencies, but as you said, over 95% of them are centralised and are essentially shitcoins. I would probably agree with you that to be fair, these coins cannot be called other than cryptocurrencies, but there really aren't many real coins if the SEC has now often started calling cryptocurrency securities. It seems to me that all coins with the POW algorithm are cryptocurrencies, the rest are derivatives.