you need to get function with the index you found;

  var func = functions.indexOf(options.indexOf(this.state.type));// this returns index not the actual func
  functions[func] && functionsfunc

My Approach would be like;

  getBTC = () => {
    // .....
  };

  getETH = () => {
    // .....
  };

  getADA = () => {
    // .....
  };

  getCoin = (type) => {
    switch(type) {
    case "BTC": this.getBTC()
      return
    case "ADA":...
    ...
    ...
    }

  componentDidMount() {
    this.getCoin(this.state.type)
  }

You can create an arrow function if you want, and your code would become:

<button value={item} onClick={(e) => this.handleClick(e, item)}>
  {item.enrollment}
</button>

And then obviously modify the handleClick function to accept a second parameter, item.

Basically, what the (e) => handleClick(e, item) does is create the following function in place:

function (e) {
  return handleClick(e, item);
}

You just initialise input as a string so just keep input for keeping input value not result data. You can create another state for keeping result OR put result data back on Data variable.

Here I am showing you to keep result data separate.

import React, { useState, useEffect } from "react";
import ListItem from "./ListItem";

const List = () => {
  const [data, setData] = useState();
  const [searchResult, setSearchResult] = useState();
  const [input, setInput] = useState("");

  const onInputChange = (event) => {
    setInput(event.target.value);
    const value = event.target.value.toLowerCase();
    let result = [];
    result = data.filter((item) =>
      item.name.toLowerCase().includes(value.toLowerCase())
    );
    setSearchResult(result);
  };

  useEffect(() => {
    const getData = async () => {
      const response = await fetch(
        "https://rickandmortyapi.com/api/character/"
      );
      const obj = await response.json();
      setData(obj.results);
    };
    getData();
  }, []);

  return (
    <div>
      <input type="text" name={input} onChange={onInputChange}></input>
      {input===""? data &&
        data.map((item) => {
          return <ListItem key={item.id} character={item} />;
        }):
        searchResult &&
        searchResult.map((item) => {
          return <ListItem key={item.id} character={item} />;
        })
        }
    </div>
  );
};
export default List;

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>

This is separating your original data and search result different.

Data can be passed to components via props.

https://facebook.github.io/react/tutorial/tutorial.html#passing-data-through-props

In your case props would be accessed inside the components via this.props.

<TodoList /> takes a prop called items which is an array. Inside <TodoList /> you can map through that array and return elements.

For example in the render method of your class you would return TodoList with a prop of items:

const myItems = [{ name: 'item 1' }, { name: 'item2' }];
function MyApp() {
    return (
       <TodoList items={myItems} />
    );
}

Then in TodoList you map the items

function TodoList({ items }) {
    return items.map(item => (
        <h1>{item.name}</h1>
    ));
}