Hm. I think you should come up with a background story for those little guys. Give them a little meaning behind the characters. Just so people can have an idea what the importance of the little characters are. I mean, If you're trying to get people to adopt them, they need to have some sort of significance. Like, the designs are cute, but it seems to me that the designs don't seem all that important to you since you don't have a personal character of that design yourself. So, it kind of makes the other people (i.e. me) say, "that's cute, but... why would I want it?" sorta like someone trying to sell random made up creature dolls and you have no idea where they came from. Unless they're sprinkled with a huge amount of "I"M GOING TO MAKE YOU WANT ME" magic, then people are just going to pass them by. I'm not saying this to be harsh, but if you really want to get them adopted, you might want to create a little world for them, and show them interacting with each other to get people interested in them since they are you're own creature design.
Well actually I was thinking of making one for myself. I drew a picture of one... I just don't know. People create random things like this all the time without giving them a background and they sell as long as the artist is popular.
It's because the artist's popularity adds a lot more value to it. Sorta like buying some kind of main stream song. The song could make no sense what so ever and have strange music to it, but people would still buy it if it came from a really famous band. I mean, the people I see just selling random stuff usually have like 100,000+ page views. Or just really well, know around Deviantart. Don't be too hard on yourself.