If the low income earners were included two things would be clear. 1) Many low income earners don't pay federal income taxes at all, many actually get paid by the IRS instead 2) Low income earners actually still benefit by getting either lower taxes or higher credits.
The only example I saw of a regular person was in the Bloomberg article that was mentioned. https://www.bloomberg.com/news/articles/2017-12-20/how-the-t... The "renter in Milwaukee" went from paying $515 to actually being credited $400.
At this point, there is no way of having a reduction in tax bills that doesn't overwhelming favor the top 50% of earners, because they pay almost all the federal income taxes. In 2015 the top 50% of those that filed tax returns paid over 97% of income taxes (the last table cell at the bottom all the way on the right https://www.irs.gov/pub/irs-soi/15in03etr.xls )
EDIT: Based on experience on this board I knew this post would be downvoted, but I'm not exactly sure why. Please help make me a better contributor by telling me what I did wrong as you downvote, thanks!