Would a massive "Impeach Trump!" protest be more on point?

No. It would be the same problem. Protesting to show that think the President should be someone other than Donald Trump is rather pointless. There's no realistic method by which that could happen.

We don't have a parliamentary system, where if a Prime Minister significantly loses support after taking office it is possible (and indeed likely) that they might be forced out. We have a Presidential system, where the head of government is separately elected and for a fixed term. In our system, communicating that you generally think the President is terrible can't lead to any actual changes - we don't have a House of Commons to consider changing who the PM is, and so there's no vector for that popular expression to manifest in any actual change.

In protest movements like the Civil Rights Movement, there's a specific agenda and set of policies that lawmakers can consider and say, "huh, if we don't do X these people are going to keep protesting," and where they might actually be able to do X. There's a specific thing that the protestors want, and a plausible way to give it to them. Moreover, because the protests were structured within an actual movement that had organization and leaders, there were specific people that were conferred power and legitimacy by the number of people they could call into the streets. BLM had a similar discrete set of issues that the 2020 protests were about, which made that moment a little more powerful (but it, too, was crippled by the decentralized nature and lack of any real leadership structure).

These types of inchoate Hashtag activism events can't translate into actual power. When you're out there protesting everything all at once, there's nothing that anyone can point to and say, "This is what we need to do to get the protests to stop." Saying, "We want Trump to stop being President" isn't going to do anything. "We want Trump to stop acting like a King" won't really do anything either, because (again) it's just too broad to translate into action.