On race probably true but its much more urban than country thus why more Democrat. Ohio & Missouri for a long time were quite representative thus why bellwether. But as GOP gained a lock on white Evangelicals, Missouri drifted away while Ohio drifted away when education became more important in voting patterns. Both have Black populations close to national average so were racially similar but now whiter as both have a Hispanic population much smaller than national average.
I would say actually Pennsylvania is probably closest to national average even if imperfect.
In 1980 when the US was 12% Black, 6% Hispanic and 3% Asian Ohio and Missouri looked reasonably close to the demographic average. But with Hispanics becoming the largest minority and Hispanics and Asians together growing from less than 10% to about over a quarter of the US population, these states are much reflective of modern US demographics.
