That's cool and all, but isn't it too much parallelism that Gagarin is still the first (Soviet) man in space, despite the early POD of your timeline and very different rocket developments ?
A fair point, and something I thought about for a while, but in the end I came back to Yuri. The Soviet rocket programme was pretty heavily compartmentalised in the 1950s to early ‘60s, so I couldn’t see any strong reason why the (significant) changes introduced to ICBM development would stop young Yuri from joining the Air Force and serving pretty much as per OTL. ITTL the Soviet space programme starts looking for cosmonaut candidates at about the same time from basically the same pool (the Air Force) with the same criteria (excellent physical shape plus suitably humble background for political reasons), so turns up mostly the same people. IOTL, Gagarin was considered far and away the best choice by just about everyone, including the other cosmonauts, so I assumed he’d similarly excel ITTL. So, In Spite of a Nail, I gave Gagarin his chance.
Other opinions are of course available