How did Newton come up with the three laws of motion? Are these laws are true of newton, or they are of Galileo.
The nature of the surviving evidence makes it hard to tell 'how Newton came up with his laws of motion': much of the evidence is in the successive verbal formulations of Newton's successive drafts, which often don't reveal much of his background thinking. Also, in the 'Principia' the laws of motion have the alternative title 'axioms'. One of the curiosities about them is that even though in retrospect they have been recognised as a highly original compilation, Newton did not seem to claim much by way of authorship of them: thus he concluded the statement of the axioms or laws of motion with a 'scholium' beginning: 'The principles I have set forth are accepted by mathematicians and confirmed by experiments of many kinds. ....' and he went on to acknowledge work or books by Galileo, Wren, Wallis, Huygens and Mariotte. There is a body of opinion tending to the view that Newton was being unduly modest about this, and it is worth looking at R S Westfall's "Force in Newton's Physics : the science of dynamics in the seventeenth century" (1971) to see why. It devotes chapters to detailed studies of the dynamics (or kinematics) of Galileo, Descartes and Huygens among others, as well as to Newton.
(This is the kind of question on which wikipedia is sometimes not at its strongest, better to trust the linked sources than the wp article itself, which in this case doesn't cite Westfall's work and begins by anachronistically mis-stating the laws themselves.) Better to read the laws as Newton wrote them, plus their explanatory passages, directly from 'Principia' iself, for which there's a good 1729 English translation free of copyright restrictions. The wikipedia article on the Principia (https://en.wikipedia.org/wiki/Philosophiæ_Naturalis_Principia_Mathematica) has plenty of links to different parts of it, such as (https://books.google.co.uk/books?id=Tm0FAAAAQAAJ&pg=PA19) for the laws of motion themselves, but please read on to cover the references to 'accelerative force' etc.
The problem of the motion of the planets and satellites. Moon, first of all. Also comets. To justify the inverse square law, Newton had to develop mechanics. His three laws summarize in a short, clear and elegant form what was known on mechanics. Then he could combine them with the gravitation law to compute the orbits of the planets, satellites and comets.