You're assuming that the Russians have been incapable of learning things throughout this war or that there has been no mobilization since those retreats or that Ukraine has been unable to defend its towns and settlements in the Donbass.
I'm not assuming that. I'm just noting some observable facts. The war has been going on nearly 3 years now and weaknesses are still being observed today. Ukraine walking into Kursk is a fine example of that.
Do you expecr Russia to run out of men before Ukraine does?
You know full well that wars aren't won strictly by how many soldiers a nation has.
If it's not about US hegemony why didn't Ukraine choose neutrality which is what Russia offered because it feared Ukraine joining NATO?
Like most other Baltic states, many of these nations underwent decades of control under the Soviet Union. Part of the reason is simply a desire to be free and sovereign from that past. Something these nations reiterate at some frequency.
Neutrality does not guarantee safety or sovereignty. The annexing of crimea is a demonstration of that.
Or look at Finland and Sweden. Notice how quickly they moved to NATO in recent years despite longstanding forms of neutrality. The reason is not because of "US hegemony", rather the reason is that Russia is sowing fear in its neighbors with its military aggression. Annexing Crimea, funding militants in the Donbas, the invasion of Georgia, the invasion of Ukraine, its well known discontent with Latvia, Estonia, and Lithuania (which also may be invaded by Russia in our lifetime), among other issues.
People simply don't trust Putin. And accepting neutrality on his terms, is a compromise of Ukraine's sovereignty.
Putins recent invasion of Georgia is another example of this. Russia stepping in militarily to manipulate a nations sovereignty, particularly of pre-soviet union nations. These military adventures of course are sowing distrust among all of these Baltic nations.