Those are not investments, you do not get a percentage of the company. Those are donations with a gift. What you get out is a gift, t-shirt, your name in the credits, prototype, free account before everyone else, etc...
People can pay $5,000 for a prototype of a drone they helped back on Kickstarter but that $5,000 is not equity, nor a gamble. It's a donation. The backer knows they are kissing that $5,000 good bye and are only given a chance at receiving a prototype drone. It's a donation with a gift.
An investment is when there is an expected return. I put in $5,000 but I expect to one day receive that $5,000 or more back. I own a tiny piece of the company. To help the average person know what they're getting themselves into the SEC has specified rules that a company must follow in order to solicit and accept public investors (aka going public / IPO). They MUST release certain financial information at certain time intervals, they must use certain accounting methods so as to not hide money, not hide profit, not hide losses, and discourage insider trading, etc...
If a company hides losses it causes a huge mess (ENRON).
So is there a Kickstarter for companies that are public and allow the average person to "invest" in them?
Yes, Scottrade & E-trade & stock brokers are basically the kickstarters of public companies. Those companies are all public and registered and you can go and see how they've been doing historically and invest however much you want in them.