I'm not really romanticizing him. I specifically pointed out that since he wasn't exactly trained in diplomacy, administration, or statecraft, he was pretty constantly alienating people and that did not help him or his position.
I was more just writing it from the perspective of if he had already been elected as a nod to the success of a local democracy. To be clear, while I think Lumumba would in such a scenario be remembered fondly as a "common man trying his best", his best scenario is just getting his nation in the right position and then honoring term limits and someone more competent taking over afterwards.
On the other hand, I think you're idealizing what would probably happen for an anti-communist/anti-imperialist alternative, especially as you're just inventing a hypothetical person without any real historical backing to your proposal. As I mentioned, the US at the time was extremely jumpy and often presumed "anti-Imperialist" was "pro-communist". See: basically most of Eisenhower's foreign policy decisions in Latin America as democratically elected leaders did mild land reform against US-based companies and immediately got portrayed as "communist sympathizers", and any Congolese attempts to try and carve profits from Belgian-owned companies could easily fall afoul of that. Until Eisenhower is out, I don't think that offer from the US is really going to lead to a prosperous and democratic Congo, and at least in the 50s/60s/and possibly early 70s their best bet is to side in some capacity with the USSR, the biggest threat in that case being a Communist movement rising to power as a puppet of Moscow, but that wasn't always the case with USSR-aligned countries.
Now, longer term, that's open to change. If Nixon can exploit the Sino-Soviet Split, a lot of presidents could achieve rapprochement with Congo with the right terms. The best timeline is get the USSR to back them to the hilt in the early years, then exploit a moment in the 70s or 80s to realign as neutral or US-aligned and collect from both sides while building internal stability and prosperity to keep the government in control.