Pierre Laval was born in 1883 in the small village of Châteldon, a rural commune in Auvergne, a region in south central France. He was the son of a local butcher. His birth certificate (left page) indicates that he was born in his parents' home, which rules out adoption or a switch at the hospital. His family tree is well established up to the 17th century and mostly comprises farmers and sharecroppers, who were all born in a handful of villages in a 10 km radius (Châteldon, Limons, Puy Guillaume).
Here are the military files of his brother Jean (who was killed at the front in September 1914) and of his father Gilbert: both are described as having "brown hair" (châtain) and "dark brown hair" (chatain foncé) and not black. Gilbert Laval's skin colour is described as "good" (others are "ordinary", "pale", "pallid", "dark", "coloured" - remember that most of these men were farmers who spent their lives outdoors).
Pierre Laval may look "Indian" on pictures due to his straight dark hair (much less so in videos, see here at 5:00) but there's no way his origins were anything but European, and above all Auvergnat.