You're acting like it's only some small fringe of voters which believe these things. It's not.
Nearly 1/3 of the country think the Earth is less than 10,000 years old.
Most people I've personally talked to about voting for the MAGA candidate have said one or more of these things. The others are usually wealthy people happy for their tax cuts. As mentioned earlier, I've had close friends and relatives refuse to associate with me because I've voted D a few times in my life and obviously do the work of Satan. This isn't some fringe rare thing, if it was would most TV ads I see against Talarico appeal to these fears? If this was truly some fringe why would the President constantly hammer these points?
The answer is, it's not rare. This is the new base of the GOP. The same people who knew Obama was a Muslim from Kenya.
Let's say these people really are some statistically irrelevant percentage of the population. Let's say it really is just that normal, sane, middle class Joe's are truly the people the D's need to target more. How on earth are the R's the better choice for them? This is the party which cuts their healthcare, works to defund their public education, cutting access to college, is even more in bed with corporate interests, is even more obviously corrupt, and overall has had power more and delivered less for the common person. How does it make sense to vote that way?
For a real concrete and recent example, can you explain the voting base for Paxton versus Talarico? Why would that average Joe voter support Paxton over Talarico?