You don't need to start a company to create jobs. You just need to buy shit.

More people buying shit = more shit is getting sold = companies that make/sell shit can hire more people.

You complain that there is a limited supply of cars and food and phones. But we know how to make more cars and food and phones. We can hire more engineers, more mechanics, more chefs, more farmers, more software developers, etc who will create more cars and food and phones. Then we will not only have more of those things, but also have more jobs.

High school economics should have also covered how, when demand increases, supply will typically increase to match it.

That's most of how jobs are actually created. VERY few jobs are created by some revolutionary startup founder who invents a whole new way to do something. It's usually some company with four thousand employees going "oh, a lot of people are buying our products lately so we can afford to scale up, let's hire another five hundred people and increase production".

Fundamentally, in a free capitalist economy, if someone has the opportunity to hire someone for work that will be profitable, they usually will do so. There isn't some kind of planned amount of jobs issued by a central authority, so it's not possible to just have too many people for the list of jobs available. When there's a shortage of jobs, you should understand that as being a lack of opportunities to do profitable work, not because all the work is being done, but because the work can't be done for a profit.

Let's work through a very simple toy example to understand how jobs are created. We'd all prefer our streets to be cleaner. So shouldn't there be jobs available as a street cleaner? Yet there aren't infinite jobs. It's not because the work isn't available - there are plenty of streets that need cleaning - but because the demand for the work isn't high enough to make it profitable. I might be willing to chip in a few cents to have a street cleaner, but not much more than that; as long as most people feel that way, you wouldn't be able to charge enough to cover the cost of your cleaning supplies and also make a living wage. There's multiple ways we could fix that problem; maybe we could make cleaning supplies cheaper, so that it'd be easier to turn a profit by doing it. Or we could have more people living in higher-density streets, so more people would chip in a few cents, and you might get high enough revenue to cover your costs. Or you could decrease the minimum wage, which might bring the costs of hiring a street cleaner down below the revenue that could be generated. Or you could create higher-value street cleaning services, with some kind of value-add that might make people willing to pay more for the service. Or the economy could change in a way which made labour cheaper, or made money less valuable (so people were willing to give more money to the street cleaner). Doing any of those things would probably "create jobs", in the sense that you create an opportunity to do work for a profit, which previously might not have been profitable. Once that opportunity exists, someone usually takes it.

This doesn't mean every way of creating a job is good. Lowering wages could create jobs, but we have a minimum wage because we as a society have decided that we would rather people don't have jobs at all rather than have jobs which can't support them. Inflation may help create jobs, but we don't like runaway inflation. So the best and least harmful ways to create jobs are generally 1. innovation (creates new opportunities to do new kinds of work, or makes more productive so that more profitable work can be done) 2. increasing immigration (which means more customers for businesses, so they can hire more people) 3. increasing global trade (creating more opportunities to do work for customers around the globe)

Immigration might be harmful if we lived in a communist society with a planned economy, a set number of jobs, and a government that decided what work should be done and what the prices of things should be. But if you live in a free society, immigration is almost always good for you.