Earlier quoted context omitted.
"Unceded land" means that because 100+ years ago the British settled as they wanted without asking for permission, the land actually still belongs to indigenous people, and not to Canadians, not to the people who currently live on it. "Unceded land" isn't exactly a legal concept, it's more of an activist slogan from people who want to see all public land (e.g. >90% of BC) privatized based on race, or want to hold the…
> Legally, Canada does have title to the land is that under Canadian law? Was this land openly sold | gifted to Canada or staked and claimed despite prior occupation? I recognise the current state of affairs, etc. but this "Legally Canada owns the land" is at root just a way of saying "might makes right, we took it, it's ours now, and we will shoot or imprison anyone who says otherwise".
That's how it works, sadly. Everywhere, not just here. The part you're missing is that "we" – the people living in Canada today – did not steal anyone's land. Certainly neither myself nor my ancestors. The original British settlers who stole the land are not us, they are long dead.
You can always look into the past to find injustices to use as an excuse to perpetuate horrible things in the present. Look at just about any conflict, modern or historical, the aggression today is always justified by something in the past. That doesn't mean that this is the right thing to do.
The right thing to do, is to lift up the people disadvantaged by past injustices, without resorting to race based division, e.g. target support by economic status instead of race. Sadly that's the opposite of what we're seeing in Canada nowadays.