The article describes several ways that various seemingly simple mathematical objects like integer are defined in set theory using complex combinations of sets

The article describes several ways that various seemingly simple mathematical objects like integer are defined in set theory using complex combinations of sets and I believe the inelegance of such constructions is the main motivation. The thing is, any constructive definition of (almost)all mathematical objects is likely to share this kind of inelegance imo. But I don't think anyone has come up with an alternative to this.