Mixkit offers lots of FREE assets which includes video clips, music & sound effects. This set has 21 subjects and 526 pieces totally that those styles of illustrations are different in each subjects. You could pick someone for match your needs, also could be the reference of your creation.

Most vectors and resources are free for download and ONLY personal use that some of them even allowed commercial purpose. NOTICED, not all files have permitted rights for commercial purpose. Suggests you confirm license on original website before any editing, modification or attributing.