But they also do different things:
You need insurance companies for one-off risks. Someone has to go see the house and say, "yep, it burned down." Also, we don't let people bet on other people's houses burning down for good reason.
Other risks are more impersonal, like "what if this company I bought a bond from goes bankrupt" or "what if the price of corn drops in half" or "what if the price of oil doubles." There are lots of people and companies who might want to hedge against those, not just the owner of the property.
Because this is more efficient and useful.
But "like insurance" I think was meant as a broader term. Traditional insurance contracts look a bit like options. But forward purchases or sales are also often used as "insurance". The big gain is that purely cash settled contracts (or contracts where cash settlement is possible as a result of sufficient market liquidity existing to allow closing a position before physical settlement) can be used for risk mitigation in other ways which offer much better liquidity and better cost-efficiency in the right markets.
A good real world example is oil price hedging. An airline might want to mitigate the risk that their future cost of jet A-1 goes up. On the other hand, an oil producer might want to mitigate the risk that their future sale price of a particular blend of their crude goes down. Instead of using insurance or entering into bilateral forward contracts, both can trade futures or options on a standardised crude (which neither of them is ever planning to physically deliver or take delivery of[0]). The contract they are trading will not be a perfect hedge for either of them, but it will mitigate their risk significantly. In fact if they are both large enough, bilaterally the liquidity available to them would likely be insufficient to mitigate the same amount of risk.
Having a "single", transparent price also brings some other benefits beyond simple liquidity. For example, it enables several ways to manage counterparty credit risk which would otherwise be unavailable (daily margining, use of central counterparties or clearing, etc).
[0] although the contract might enable an oil producer to make physical delivery of their own blend with a price adjustment
Loans are useful and necessary because businesses need to buy things before they get paid. It can't all be done using Kickstarter! Farming works this way.
Insurance is useful because you get paid when something bad happens to you. On a day when you're glad that you had insurance, it means someone else lost a bet.
Buying insurance you don't actually need is kind of dumb because you'll lose on average, but people do sometimes win in casinos, too. Selling insurance when you can't afford to lose is risking disaster, but sometimes people get away with that too.