Maybe you don’t agree with this definition, but in a list of events that is generally mentioned as genocide we should not limit ourselves to the most narrow definition. That would sweep too many atrocious acts under the rug. The article on the genocide should make it clear what actually happened, meaning you shouldn’t think “every single person got murdered” if you read genocide in a title.
By the more broad definition of genocide there shouldn’t be much doubt about who started it. Israel is a religious colonial project that sought to displace non-Jewish people in that area from its inception. There’s not really any secret or controversy about this except by those who try to distort history. You’ll find many Israeli openly talking and writing about these goals. You’ll also find Jewish people, even ones living in Israel saying the state should never have existed to begin with for these reasons and others.
Yes, it’s more complicated than what can be summarised in a comment. There is blame on both sides. But throughout recent history only Israel has been in a position of power to solve the issue and yet they’ve repeatedly and wilfully sabotaged anything that could lead to either a two or a (fair) one state solution. Again: they’re talking openly about this and why they’re doing it: there’s too many Palestine people. They can’t be integrated into Isreal or be given too much power as an independent state because it would threaten Israel as a religious project whose only purpose is to create a state primarily for Jewish people.
The goal is explicitly to destroy Palestine and its people. It always has been, even if they don’t say so out loud when the audience is non-Jewish. Doesn’t mean they want to kill them all.
It’s kind of insane that we recognise religious ethnostates as a very, very bad idea for all other countries, yet give Israel a free pass.