To my knowledge I would agree, I don’t believe Lafayette was revered so much for his military prowess (as say, Baron von Steuben, for example). Lafayette did have good political influence, and as you mention helped in part secure French support which was key. I also think he helped from a figure-head standpoint. He carried himself well, was respected by Washington, and was a leader that could be looked up to in what became a multinational (French, Spanish, US) cause for freedom.
I do wonder, however, if the Marquis never got involved, if some other influence might have come into play just the same. A small change of events here or there and some of the more prominent contributors might not have found themselves in the same place. In hindsight it is easy to see how large a role they played, though possible to consider that maybe someone else might have stepped up in a different way. It is also wild to think that maybe had things not happened as they had, a key contributor/event different here or there, the war might have been lost by the US. Ah, the reflection on history 🙂