Assad succeeded his father, his first two elections were uncontested, nobody gets 99% of the vote fairly. He has committed war crimes against his own people, including the use of sarin gas. By far the largest opposition to the Assad regime are the SDF which is mostly Kurds and who control 27% of the country, ISIL, by contrast, only control 2%. The uprising was started by the Free Syrian Army, formed by defected Syrian army officers, in July 2011. ISIL didn't become a significant player until two years later.