Lizardfolk often have unique beliefs and/or quirks that inform their worldview. At their core, they tend to view other humanoids with an indifference verging on pity. When playing a lizardfolk, you should select (from Volo's Guide to Monsters) or create a quirk to help inform the way you perceive and interact with other humanoids and worldly things. Note: case in point, there is currently a Lizardfolk PC in a weekly campaign that views other creatures literally as "meat" until they prove useful.
First-party traits for the Lizardfolk can be found on page 112 of Volo's Guide to Monsters and is copyright Wizards of the Coast.