First off, you used France's colonialism to point out USA issues.
Second, USA could have leveled Japan (we did not, we rebuilt them), we could have claimed all those islands in the Pacific, but no they are independent today, we could have kept the Philippines but we let them go, we could have kept slavery, but no Americans fought to end it, we could have ended Germany and Europe, but no we did the Marshall Plan and rebuilt them. Latin America complained they didn't get paid so we even gave them money to rebuild. We could have built a colonial empire larger than the British if we wanted (notably after WW2) but no, the USA didn't and encouraged colonialism.
If we were what you said, we would have supported UK and France in Suez conflict, kept Segregation, kept the Philippines, kept half the territory we occupied in 1945, etc.
Funny thing is, that I sometimes wish the United States would be more like you say and go Roman Empire or worse. If USA went 1939 Germany on the world, we might not be stopped because unlike Germany, we have a navy and oil.