Centre-left doesn’t mean the Left. It just means it’s to the left of the other centrist party (Tories). Just because they lean left doesn’t mean they are the Left, Radical Left, Commies etc
PS You have be to be pretty extreme to think the Labour party isn't "left" enough for you. As in, I'm not sure what else they could do to appease the far left in practice without sever negative consequences for the UK.
Have you looked at actions rather than manifesto? There's very little change in policy actions from the previous non-Labor government, so it doesn't track unless you see the tories as left wing. Which is clearly more extreme.