Who is the first moshling and how do you get it

There isn't a first Moshling, as such, as you attract Moshlings in the order you want.

To attract Moshlings you need to plant three seeds in your garden. You buy seeds from the stand on Main Street or at the Port. Each Moshling has a different combination so you need to work out the correct combination to attract the Moshling that you want. Keep planting seeds until you work it out!