The vast, overwhelming majority of the 2019 Tory vote is still alive and leans to the right. Doesn't mean the Tories will them all of course, but it does mean that it's Labour that has to climb the hill, while the Tories need to turn out their 2019 vote.
Sadly this is true. Apathetic voters are still apathetic after years of hearing Labour are Holocaust-lovers, and old voters will still vote their wallet rather than their morals.
Labour has a steep slope ahead of it to win back any of the '17-'19 Con voters, and right now past polling errors point to a hung parliament in 2024.