What does Lennie do in the book "Of Mice and Men" to make him known as "kind"?

It's not entirely clear why Lennie would be described as "kind." He certainly has a gentle, child-like quality to him. But that's because he appears to have the mental age of a child, whereas kindness implies deliberation and moral self-awareness, and Lennie simply doesn't have any understanding of what this means. An act is kind by virtue of the act itself rather than its consequences. Lennie, however, doesn't understand this, either.
No doubt there's a certain tenderness to Lennie's acts; he gently strokes anything soft, whether it's dead mice, rabbits, or Curley's wife's dress. Yet the consequences of his doing so are invariably damaging. Lennie and George had to leave the previous town they were in because Lennie touched a girl's dress. He meant no harm, but clearly she got the wrong idea. And the dead mice that Lennie strokes in his pocket are only that way because he killed them. Not on purpose, of course, but because Lennie wasn't aware of his own strength when he nipped their tiny heads between his fingers. Also, Lennie's gentle touching of Curley's wife's dress ends in tragic consequences.