You can get a sense of the possibilities from looking at some of these past Storybooks about heroes and heroines. Of course, there may be many other characters that are heroes or heroines in your eyes, and you could focus your Storybook on explaining just what it mean to be a hero, choosing your favorite stories to convey your ideas.
Here are some Wikipedia links to some of the heroes and heroines of the Ramayana: Hanuman - Lakshmana - Rama - Sita.
And here are some articles about heroes and heroines of the Mahabharata: Arjuna - Bhima - Draupadi - Krishna.
There are also some related topics you might consider:
Dharma. A crucial element of heroism in the Indian tradition is Dharma, justice, so you might get some good ideas about hero stories by looking at the page about Dharma.
Avatars. Two of the characters listed as heroes here, Rama and Krishna, are avatars of the god Vishnu, and the heroism of Vishnu's different avatars can make a great Storybook topic; for more about Vishnu, see the page about gods and goddesses.
Women. If you are especially interested in heroines in the epics, be sure to check out the page about women, where you will find many female characters with heroic qualities, even if they are not always front-and-center.
Brothers. You might also have noticed that I have listed two brothers from each epic here - Rama and Lakshmana, Arjuna and Bhima - and the page about families might give you some more ideas about brothers-as-heroes. Both the Ramayana and the Mahabharata feature many sets of brothers, both as heroes and as villains!
Rakshasas. The gods, goddesses, and also the humans are often doing battle against rakshasas (demons), so you might also want to look at the page about rakshasas to see what kind of hero stories you find there.
The image below shows the goddess Durga battling demons: