Yes, of course there may have been other groups of humans in the new world before the land bridge peoples arrived. It is just that the land bridge people were the ones who made a lasting impression on the “America’s.” Earlier groups may have been from Europe or Asia or Pacific Oceana.
With regards to the land bridge peoples: some of those Asians who crossed over the land bridge into the Americas may have included Indo-Europeans who were a part of the group who walked across the land bridge into what is now Alaska and Canada.
Ancient baby’s DNA reveals completely unknown branch of Native American family tree
The genome of an infant buried 11,500 years ago reveals a newly discovered group of ancient people
By Rachel Becker Jan 3, 2018, 4:57pm EST
https://www.theverge.com/2018/1/3/16846644/genome-ancient-beringians-baby-bones-dna-native-american-human-origins-alaska-siberia