Yes, they had incredible techniques. They could detect a remote island by the way the swell is disrupted. Also recently read about Magellan's voyage and it is remarkable that they made it.
They set themselves a task that they weren't up to, and they failed at it. It doesn't make sense to say "it is remarkable that they made it", because they didn't make it.
You know this happened 500 years ago, right? If someone did this today and had that death rate, I would absolutely agree, but the challenges then were drastically different. No, not everyone made it, but those who did were the first to circumnavigate the planet - and they very much did make it.
A little off topic, but as a reminder of how different the world used to be: families used to move across the US on foot, maybe with a wagon carrying their supplies, and many died doing so. I'm quite thankful I can just get on a plane to see my family :).
Also, as someone who needs to remind themselves occasionally to be less negative, I would encourage you to be less negative about things that aren't 100% a success.
P.S. If you really want to hate on Magellan it would make sense to do so for something like him burning a village in Mactan because they didn't want to convert to Catholicism[0], not this. You may be pleased to hear that this directly led to his death.
By any metric related to exploration they were wildly successful. The amount of information that was gathered and relayed on a single voyage at that point in history was astounding, and the story was incredible.
