As for some bots that have already been made, there are a few examples in the OP.
Are these strategies strategies that you created, that were created by users and given out for free or does strategies are visible by default?
I only wonder since when a strategy would be really good then it could get saturated pretty fast by others using the same script.
Those are example strategies, more to provide some code and tricks in pine for making your own custom one. Some of them are being used by others, but there is almost always some minor customizations at bare minimum. Different time frames, different markets, take profit, stop losses, etc... The odds of more than a few people running an "exact" system are pretty slim considering the wide range of indicators and possibilities on TradingView.
You can go to this link and there are always new people adding new strategies that can be automated.
https://www.tradingview.com/script/?sort=recent&script_type=strategies