You can get a more holistic view using, say, quintiles: (grabbed off Wikipedia)
42% of children born to parents in the bottom fifth of the income distribution ("quintile") remain in the bottom, while 39% born to parents in the top fifth remain at the top.[5] Only half of the generation studied exceeded their parents economic standing by moving up one or more quintiles.[5] Moving between quintiles is more frequent in the middle quintiles (2-4) than in the lowest and highest quintiles. Of those in one of the quintiles 2-4 in 1996, approximately 35% stayed in the same quintile; and approximately 22% went up one quintile or down one quintile (moves of more than one quintile are rarer). 39% of those who were born into the top quintile as children in 1968 are likely to stay there, and 23% end up in the fourth quintile.[5]
Children previously from lower-income families had only a 1% chance of having an income that ranks in the top 5%.[7] On the other hand, the children of wealthy families have a 22% chance of reaching the top 5%.[7]
EDIT to add some sources:
> The key observation, based on a growing body of research, is that when it comes to upward social mobility, the U.S. is truly exceptional — that is, it performs exceptionally badly.
https://www.nytimes.com/2019/02/28/opinion/ivanka-trump-soci...
> Although the discovery of America’s low mobility, compared to similar countries, is relatively new, it turns out that mobility’s been low for some time.
http://www.msnbc.com/msnbc/us-social-mobility-problem
> A new study indicates that from the 1980s to the 2000s, it became less likely that a worker could move up the income ladder.
https://www.theatlantic.com/business/archive/2016/07/social-...
This is a distraction from the problem of wealth concentration and lack of mobility in the United States by saying: Yeah, well, you’re richer than the Haitians, so quit whining. Being part of the largest economy in the world, I would certainly hope the poorest in my country, would be better off than the those in the least developed country in the Western Hemisphere.
https://en.wikipedia.org/wiki/Socioeconomic_mobility_in_the_...
WRT intergenerational mobility, the US does quite poorly when compared to other modern economies, with a very strong correlation between parental wealth and the child’s wealth. For instance 42% born into the bottom quintile, stay there in the United States, but only 25% remained in Denmark. 8% rose to the top in US, but again, 14% did in Denmark.
Intragenerational mobility in my opinion is a bit of a red herring. Often you’ll hear someone trumpet some number about people moving from one group to another in a single year, but you have to look closer to the reasons why. Some people are just on the cusp of the cutoffs and so will bounce around it. Others are experiencing temporary outlays, and will very quickly return to their original levels. Unless the person’s move has some stickiness, along with some large absolute change, it’s meaningless noise.