It's a maudlin piece of credulous mainstream boomer-worshipping horseshit.
It's underlying message is that even if you're dumb as a post, as long as you exhibit US values (enlist in the army, do what you're told, be Christian, salute the flag) you will be rewarded with fame, riches, children, and get to meet all the rockstars and even Presidents that walk the earth at the same time as you.
If you try to fight the system or get involved with the counterculture, like Jenny does, you will literally catch AIDS and die. Subtle.
The movie also can't resist making the Black Panthers into a hate group, which is probably exactly how white baby-boomers, by and for whom this movie was clearly made, saw them. To say nothing of portraying anti-war protestors like assholes (the president of the Berkeley chapter of the SDS smacks Jenny around at one point for fuck's sake - which I guess is cool with the Black Panthers, who glower at Forrest brandishing firearms while kicking him out of their meeting for daring to retaliate to a woman getting beat up).
In 1995 The National Fucking Review named it one of the "Best Conservative Movies" of all time, then in 2009, ranked it number four on its "25 Best Conservative Movies of the Last 25 Years" list.
Let's hear from them about how great this movie is!