Need help understanding eth – control

I’ve been reading and learning more about crypto as I’ve started investing but I need help with one thing… who controls crypto? Using eth as the subject here, it’s a decentralized peer to peer protocol, not backed or owned by a corporation or government, and due to the nature of the protocol the blockchain is exceptionally secure and stable.

But then I hear about things like protocol changes, forks, etc. and think that somebody must have access to edit the protocol code so make these improvements. Is this one person? (The creator of eth, for instance?) if so, it seems like an extraordinary chink in the armor, as that one person could be seduced, persuaded, or coerced into damaging or destroying the entire protocol (or if he died suddenly, the network no longer can improve).

On the flip side, if it’s open source, then hypothetically anybody could do this.

Is it the miners who all vote and review the code change, then once consensus is reached they vote and eth adds the change?

I don’t think we’re at a machine learning point where the protocol improves itself, so im looking for answers.

This question stumps me when I discuss eth with family and friends and it comes up often