Gurren Lagann, which is actually called “Tengen Toppa Gurren Lagann”, is an embodiment of the shonen genre, in anime form.
Shonen series are series aimed at boys, many of them are combat/adventure heavy, series such as Bleach and Naruto. The protagonists are usually teens, who overcome their enemies, and like in Poke’Mon‘s 5th episode (I have one heck of a memory, I know), the protagonist often loses, and then through sheer guts and determination (bloody-cussedness) trains or just comes back and wins.
In Naruto Shippuuden, there’s a bit of a ridiculous moment where Team Guy faces their clones, they get kicked, and then win just because they decide to be stronger than they were yesterday… rather than just switch who they’re fighting or try new techniques. It was a serious “WTF?!” moment to me.
In Gurren Lagann, there are actually three phases to the series. It begins with the Kamina and Simon’s home community underground, and then quickly goes on war. They wage a war on the beast-men and their mecha who keep them down (both underground and stopping them from reproducing). They fight and fight and fight, and after episode 8 there’s a slight change in the atmosphere, though the fights continue.