Was it OK for Americans to kill the British ?

This is getting tedious. Just state what you want to say, providing the appropriate context, instead of chain-posing these juvenile rhetorical questions.

Just admit that you only attack the Jews for behavior you would not blame anyone else for.

I'd be lying if I admitted that. I have demonstrated against several US and UK led military incursions.

Also against the October 7th attack ?

The October 7th attack was already over before demonstrating against it could have achieved anything. I did write to Israeli friends that very day though, telling them my thoughts were with them and their families. It was about all I could do.

The demonstrations against Israel started on day one of the attack

Some of them, perhaps. Many who had followed the geopolitics of the region for a long time, who already knew, before Oct 7 what Bibi, Smotrich, Ben Gvir, etc.'s aspirations were for Gaza knew exactly what the response would be as soon as the news of the attack was heard. Even this article was Oct 8:

Meaning, even within Israel, "demonstrations" against the Bibi's government began on day one.

In Israel demonstrations against the government are allowed. You won’t get killed for it. In Gaza they are not. I prefer democracy over dictatorship.

In short, admit that you are a hypocrite