Is the United States really a developed country?

[o_O.Q]

" it has massive inequality in terms of wealth"
people are paid differently depending on their levels of competence... you think a garbage collector should be paid the same as an engineer?
income inequality obviously is a problem if the levels of poverty are very high and increasing, but statistics show that the reverse is happening

"Compared that also with no public health care."
has nothing to do with how developed a country is, just how socialised its policies are
cuba by comparison is very poor and underdeveloped and has public health care

"Also the government is much more corrupt than the other developed countries. "
which has nothing to do with whether a country is developed or not

"The government tries to prevent gay marriage and abortions from becoming acceptable. For supposedly being a secular nation the government seems to base a lot of their rulings off of religious views."
this is more complicated than you are alluding to here... but regardless, we are not living in the 1950s gay marriage and abortion are legal

"Of course this also extends to school violence. In no other country in the whole world are mass shootings in the school a problem like they are in the United States. "
well in china they have mass shooting stabbings instead... which wouldn't stop btw if guns were banned obviously

http://www.abc.net.au/news/2018-04-28/at-least-nine-young-students-killed-in-a-mass-stabbing-in-china/9706196
https://en.wikipedia.org/wiki/School_attacks_in_China_(2010%E2%80%9312)