The problem Starmer has imo is people aren't voting him into power, they are voting the conservatives out of power if that makes sense. People are more enthusiastic about getting rid of the Conservatives than excited by Labour. I saw a clip of Andrew Neil talking about this earlier and I agree with him, Labour's vote share will possibly be lower than Theresa May's in 2017, she ended up losing the Conservative majority with that vote share and that same vote share is going to win Labour a 200 seat majority. He described their margin as being as wide as the ocean but as shallow as the village pond. The Conservative vote is being split between the Conservatives. Lib Dem and Reform.
Last time when Boris won as well I think the main driver was his clarity on Brexit and that people in this country genuinely do not like Corbyn. People voted to keep Corbyn out rather than Boris in. Thing is those voters if let them down will turn on you as the Conservatives are finding out.
Starmer is not inheriting a very healthy country. He'll have to make himself unpopular with his own activists to really get the country going. He's looked very indecisive so far, hopefully when in power he'll be a lot more firm and push through the changes needed.