Webflow’s CMS structure requires the CMS slug, so there’s no native way to remove the /blogs/ portion, though you can rename it by changing the collection slug.
301 Redirects reroute a web browser request to the destination URL- meaning that you must have a meaningful page at that destination URL. I think you’re trying to “change” the URL of the page using redirects, but they don’t work that way.
In short there’s no native way to mimic those WP paths.
Standard practices for SEO is to redirect them to your new Webflow paths, e.g. /some-article → /blogs/some-article
If you really want to maintain those paths, it’s possible with a reverse proxy.
Maybe not the solution you had in mind, and maybe I’m saying the same as memetican in other words, but isn’t it more clear to set a redirect on your old blog posts, thus adapting the new subdirectory of /blog/.
This you can do by one redirect line, the other way around as the line you’ve written:
/(.*) → /blog/%1
If I’m correct this way you won’t get penalized by search engines and keep your ranking (but I’m by no means an expert), and your visitors won’t notice.
@Tookster the challenge is that a wildcard would also pick up all of the static pages like /about, /contact, /privacy-policy…
However with the new 301 import, I have wondered if the ordering of the redirect rules could be used to control that, i.e. make the wildcard match last.