I am writing my essay about how three people gave more rights to their people. My first sentence of my introduction says "Civil rights are an essential part of society." and then I continued saying that there were some groups of people who weren't receiving equal treatment and how the three people helped them.
How can I make that sentence more attention-grabbing?
What a great question. I agree with your idea that this sentence is bland, and could use more substance. Rather than provide a new sentence for you (you already have such a great start that I think you'll come up with something perfect on your own) I want to give you a few things to think about so you know just where to go.
The first thing that sticks out as too generic is "civil rights." Is there a way to describe this exact term without actually using it? Consider that as the focus for the rest of your essay, you might be using it several more times. Next, to say "essential part of society" is just too generic. For what kind or for what part of society are civil rights essential?
Sometimes, painting a picture of the opposite of the point you are making is a better attention grabber. What does a society that lacks civil rights look like? Feel free to use more than one sentence if you need. A good hook does not need to be bound by a limit on the number of sentences. I hope this helps.
You could begin with an anecdote rather than such a general statement. An effective example for civil rights is to briefly tell the story of Ruby Bridges, one of the first children to attend a newly desegregated school. A more modern example is to discuss Afghani women voting for the first time (in decades). By beginning your essay with an anecdote, you not only make it more interesting; you also more subtly address civil rights and provide an effective lead-in to your thesis statement.
The key to writing an effective introduction is not only to form it so that it logically flows into your thesis but also to think about what catches your attention. What makes you want to read something? What makes someone's writing memorable? What shows you from the very beginning that someone has something important to say? If you can keep these questions in mind as you write, you will be able to motivate your readers to enjoy your writing.