Clarence Goes Out West & Meets a Purple Horse by Jean Ekman Adams could have written (and therefore read) in the 
1980s or early 1990s. That quirky “otherness” I associate with stories of my youth. They did not have a message per say but they had the only point being about friendship. There might have been a message, but it was too hidden to see.
For me, Clarence and said purple horse has no “over-the-top” message; it is happy to be a book for fun. However, it also can be too sugary and not filling enough and therefore, not everyone’s cup of tea, but at the very least there is a purple horse.
In other words, this is a fun book that everyone takes away something from it. Maybe there is a little message about being brave, but then again, maybe not. And maybe there is a message about just because you are old does not mean you are not useful, or not. Maybe there is a message about trying new things. Or not. You decide. I think it is about a pig who plays cards, joins a cowboy band and rides a horse.
It is a story that lent itself as the first book in a group of stories. It is a story that has cartoonish illustrations that you love or not. It is a story that can be a favorite for years to come or a good just right now story. Ages 5 to 8 are probably the best audience for it and a (with help) beginning/slightly higher reader, could read as well.