I'm not big on the technical aspects of poetry, but the feelings behind this are plausible and heartfelt. I'm sorry for your loss.
You could've made more of your narrator's reaction to the death of his uncle. Did he change his attitude to the beach due to that? If so, did he draw on memories of better times and so begin to enjoy it again? Perhaps he realised that nowhere is ever entirely safe and if the sea hadn't taken his uncle then something else might have.
This is a good start for a young writer. If you want to improve it, explain why the princess is always so sad. Perhaps her father offended the same witch who turned the prince into a bear and so she's under a curse too. If not, perhaps someone she cared about died young for some reason.
This is a plausible scenario and you evoke it with vivid detail.
'As the would was being nice' should read 'as the world was being nice.'
'I got unconscious' should read 'I fell unconscious.'
Even so, you wrote some good descriptions. I like the line about dancing dolphins. Keep it up and you'll get past mistakes like those above.
You start out subtle and end it shockingly. This is a very good piece with convincing detail delivered with economy.
I like your descriptions at the beginning. Its common for authors to change their minds while doing first drafts of stories and good that you're self-critical. Perhaps you could've described the boy's escape in more detail, it would've added excitement, but overall its a good story.
If we all got upset every time something bad happened in the world, we would loose our sanity. You're not a bad person if you can't tackle every issue. Dealing with the present lockdown is a new experience even for adults. Is it any wonder a lot of people find it hard to handle. Don't break the law, this lockdown won't last forever, it can't or economies all over the world will crumble. Surely no government run by sentinent adults will allow that.
I hope things improve for you soon.