I sat one morning & wondered what would become of Africa if we never knew America existed. Below are a few things I think would exist or wouldn't exist if we never knew America existed:
1) No democratic world view: We would be back to a "speak sense or die" world view, where unwanted or undesirable people are still oppressed. Only the voices of select important people would matter. Minorities would barely be seen & LGBTQI+ movements would be unheard of.
2) No music/entertainment industry: Having no exposure to Hollywood & the USA music industry, music would likely be communised (community property) & less an individual's property. We'd have far less entertainment & might be reduced to watching just news & sport if TV existed. Music videos could be unheard of or less popular. The music & entertainment industry as we know it would not exist because selling music itself may be unprofitable in a world where people had nothing to play it with (see point 6 below).
3) No Liberia or Sierra Leone: Transatlantic slave trade would not be know so, no transatlantic slaves. Liberia & Sierra Leone cease to exist.
4) Every African nationalist movement would be far greater: As we all know in worlds where democratic world views are discouraged, the people tend to latch on to emotive philosophies far stronger & without much fact to back those philosophies. Any propaganda would virtually explode in popularity & Africa would really be a fascist's dream. Countries may even be more militant.
5) Interracial relationships would be less common: Casual interracial relationships would be far less common & if existing would be for a specific purpose.
6) Less technology: A lot of modern technology is a result of America's doing such as GPS, PCs, many internet communications tools etc. Electricity may exist but the extent of it's popularity might be limited.
These are just a few points I think may be likely in a world where we (Africa) didn't know of the existence of America or America didn't exist. You can add more but as you can imagine, it would be a very different world without America.