Moving the site from one CMS to another, + redesign, new texts. What promotion strategy to choose?

Question

Search Engine Optimization

Such a situation: The
old site has texts optimized for machines, but not for people. In the new version, the texts are optimized for people :)
The site was promoted on the first version and the old pages of the site are still hanging in search engines, and there are much more of them than new ones.
It turns out that a site optimized for people will lose positions because it is not optimized for search engines. Because on the new version, besides, there are fewer pages and less text ... So?
But the old version does not look solid for potential customers and is outright nonsense.
How to be? :)
Rewriting comes to mind. But the site of the new version is quite competently made, and nothing more. Well, i.e. no need to inflate the text...

Answer 1

Keep old URLs. Or make a bunch of redirectors. That's what's important in order not to lose your old SEO positions.
We receive links to pages that were on the site as much as 5 years ago. We catch and redirect.