From a German's perspective I want to understand: Why are racial stereotypes still so prevalent in America?

(Disclaimer: So first I wanted to emphasize and acknowledge that this can be a sensitive and emotional topic. This question is solely because I'm curious and am trying to understand it from an educational/sociological perspective. I know that a lot of people online can have a short temper but this is not a bait, I just genuinely wanna understand. I hope I will find a few more intellectual people here who won't get offended and can give a more empirical answer. And please apologize if my English is not perfect, English is not my native language and I'm just 21.)

So as a German I'm very close and familiar with the horrible actions that humanity committed in the past. I'd say compared to America who enslaved people based on their skin color Germany was way worse by mass executing and enslaving people based on their ethnicity/religion.

But there is one big difference that I don't understand: Here in Germany we are extensively educated about what happened in the 3rd Reich. It's a big part about our education to learn and understand what horrible things happened and why they happened to make sure this never happens again. This kinda lead to the point where many Germans are deeply ashamed just for being a German (even though they're quite far detached from what happened) and this is also a reason why you won't find many German flags hanging here.

So I'm not much aware about Americas education on their slavery but I experienced extensive racism and misunderstanding from Americans about race to the point where many (of course not all but many) Americans make a big deal out of race as if it defines their core personality and seem to overly obsess to the point where it seems people get different opportunities and are still to this day getting treated unfairly based on their skin. Even though every educated person knows that skin color is not changing someone's personality since we're biologically all the same race called homo sapiens sapiens and what people call "race" is not scientifically accurate but rather a social construct. This seems to go further where people still use racial slurs that have been used for slaves (like the so called n-word) and people overly focusing on skin color like saying they don't wanna be friends with white/black people or don't wanna date them. And it almost seems like it's getting worse in a way and was somewhat better maybe around the 80's.

As a German this feels very weird and wrong to many of us (I talked to many Germans about this who feel similar including Germans who lived in America for a while). Because the equivalence would be if we still continued to make a big thing out of whether someone is a Jude or not which we don't. Whether someone is a Jew or how black or white someone is, really isn't a thing at all here. Of course I'm totally aware that there are still many racist people and even neo Nazis in Germany (but also in the US and every part of the world) but the general way of thinking about "race" in everyday life seems to be very different.

Because to me this stereotype that people solely have low cognitive abilities based on their skin color is very outdated. We all have different skin, there are no lines, humans are colorful and not "black or white". I wonder if there have been strong efforts of American politics and society to get rid of these stereotypes and gain equality for everyone. Because I wonder what the reasons are why this seems like not being the case (at least to the extent it should be) and it seems unnecessarily divisive. Since to me educating about these stereotypes and not putting people into boxes is the key for getting rid of it when there is a mass willingness of people wanting to see each as people and not just as a color and finally put this behind. Might there maybe be industrial or political interests in keeping this divisiveness?

Like I said I'm very open minded and am trying to understand. Please have understandment for my perspective and try to be thoughtful in your answer.

In the end of the day I would just wish for whole humanity that we could put those toxic and destructive actions to the past and start embrace loving everyone for who they are as an individual.