For the counterfactual, imagine if we sent a bunch of HIMARS or MBTs in the first months of the conflict and now they were being paraded around by Russia on victory day.
It makes some sense to provide small arms -> light support -> progressively bigger weapons systems. It is worth remembering that at the beginning of military aid to Ukraine, there was a large chance they might have suddenly capitulated. In that event, anything you send would have immediately fallen into not-Ukrainian hands.
I think Ukraine established its will to fight within the first month and its ability to exist in two or three months or so. We should have shifted our approach around then and started planning long term.
I don't want to make any big claims because real visibility is low but I think your assessment is somewhat mistaken, and not shared by US DoD generally, which were, I believe, fairly pessimistic as recently as 3 months ago.
It makes some sense to provide small arms -> light support -> progressively bigger weapons systems. It is worth remembering that at the beginning of military aid to Ukraine, there was a large chance they might have suddenly capitulated. In that event, anything you send would have immediately fallen into not-Ukrainian hands.