you are correct, but with keepalive, 10 connections over http1 will beat 1 connection over http2[1] even 4 connections will do better.
[1] when there is high latency, or some packet loss, and the requests are batched evenly over all connections.
Each of those connections needs its own TCP and TLS handshake making a total of 6 trips. Also, although this didn't take off, h2 had push promise which could have been a big help.
Re:HTTP/2 and HTTP/3 explained
by pi-e-sigma on Thursday March 14, 2024 @02:11PM
(#39707164)
Yeah HTTP/2 push is so great that Chrome removed it.
Straight from the horse mouth: "However, it was problematic as Jake Archibald wrote about previously, and the performance benefits were often difficult to realize"
https://developer.chrome.com/blog/removing-push
All browsers cap the number of connections which are opened to a single domain (I think on IE this was 4, and has increased to 10, but it's not a large number).