While selling leads is a lot less lucrative than earning life insurance commissions, I realized over time that selling life insurance was way too much work. If I was going to keep things going, I would need to hire people, manage a team, and put in a lot of hours. I wasn’t really interested in doing any of that, which is why I opted to start selling leads instead. Now that I do, I’m bringing in passive income with hardly effort on my part.
1. The batting cage idea is very risky. I’ve seen many of them close over the years and it is not anything close to passive income if you want to keep the business going. You have to continually promote it and target youth leagues, coaches, schools etc to catch all of the new players who grow up and want to play. I’ve played at probably 8 batting cages over the years and 7 of them closed. 

Do I need to submit my site to Google?

Agreed but I might consider a blended portfolio of large and small cap stocks using low cost mutual funds (I found a fidelity large cap fund FUSVX with a net expense of .035% that has also delivered 17%+ YTD gains, some are dividend some are growth stock in the fund) UNLESS you’re close to retirement. This way you get the growth upside on small cap paired with the stablilty of some large cap stocks while maintaining balanced ricks.

Decide to invest in dividend stocks. Dividend stocks pay out a portion of the company's profits to shareholders. These dividends are paid at regular intervals, so they produce a regular income stream. Investors who hold a large amount of this type of stock are known as "income investors" because they prioritize regular dividends over stock value growth.[1]

How do I generate passive income?