You have a very happy Bird's Nest Fern. bird's nest fern Let us know what you think? Lucky you. Whatever you are doing don't change a thing.
I guess I am remiss for not explaining why these leaves are getting 'more jagged' as the plant gets older. The more mature the plant gets the more the leaves will look like the text book plant. This is completely normal, pretty much standard for all plants to have young leaves on a young plant look different than mature leaves on a mature plant. This site shows these very same oddly notched leaves on young plants.
example of similar weird edges on bird's nest fern