"Sixteenth birthday" makes no sense

I haven't seen this movie, but I know the stories (the original ones, the variations, this movie's, etc.).

I don't know why everywhere I turn, everyone keeps making the same mistakes proving they don't either have ability to think or understand basic things about this world or the ability to write simple english correctly, but it seems like almost everyone living on this particular planet is somehow mentally damaged or.. well, stupid.

HISHE made a video about this particular movie - their videos are usually good, because they show this exact problem (stupidity of people) seeping into movies so much and so deeply, any thinking individual realizes the movie, its story, etc. makes absolutely no sense. All you have to do is think for awhile to realize this about almost any movie, there's always something that would destroy the story/plot (still not sure of the difference, I guess I am not too bright, either).

For example, Back to the Future couldn't happen the way its shown, and someone as intelligent as Doc Brown should immediately (in 1955) realize how to fix everything without effort. Information about the future changes the future. This should be written down in every time travel movie script on every gd dmn page.

There are so many ways for Doc and Marty to fix the situation, there's absolutely no need to rush. WHY do they impose TIME LIMITS in TIME TRAVEL movies, even Bill and Ted's Excellent Adventure tries to do this in a completely nonsensical way by creating a rule the movie then breaks constantly.

For example, Doc could decide that instead of testing with Einstein and doing it on a parking lot he now knows the Libyans know how to find, he could just go to 1955 as soon as the time machine is ready, to give Marty some plutonium so he can get back. Easy, Marty has to do absolutely nothing.

Of course prevention would be even better - just don't friggin' invite Marty to the parking lot where you'll be shot - also, no need to test with Einstein now that you know it works, etc. etc.

But alas, even HISHE made this braindead-style mistake; they made Ariel say it is her sixteenth birthday, and the prince misinterprets this as her actually being sixteen. Hello? Isn't the day you are actually BORN much more of your birthday than any other? This means, your FIRST birthday you are 0 years old, your second birthday, you are 1 years old, and so on (well, your body is, not you, but whatever).

Sixteenth birthday = Ariel's body becomes 15 years old.
Seventeenth birthday = Ariel's body becomes 16 years old.

How the F can a famous, respected, popular youtuber channel let this kind of elementary mistake slip into such a high-profile video?

Why does ANYONE make this mistake, let alone so many?

It's almost as people don't even count your ACTUAL birthday as BIRTH-DAY, but only the ANNIVERSARIES (they shouldn't even be CALLED birthdays, if you are technical about it). It's like buying a car, but then telling everyone your car purchase day was 1 year from when you actually purchased it. What kind of sense would that make?

Could this planet's people please stop making me realize just how stupid almost everyone here is.. please, at least correct some of the most common mistakes like this.

Stop saying 'your / ur' when you mean to say 'you're / u're', stop saying 'loose', when you mean to say 'lose', stop writing 'alot', when you mean to say 'a lot' and so on.

PLEASE, is it that difficult to type something correctly in an age where all the information about everything, even good parenting and dog handling is almost literally at your fingertips (or under them)?

Why don't people research anything before reproducing or getting themselves a free dog (that they then call a 'rescue', even though that's supposed to be a verb anyway - they didn't RESCUE anything, they just got a free dog from the pound without checking the dog's energy level or psychology at all)? Just watch two episodes of Dog Whisperer, for crying out loud.

Why can people still reproduce without a license? I hate licenses and would never recommend or support them, but this is the ONE exception I am willing to make, because most people are CLEARLY TOO STUPID to bring up children in a responsible, healthy way. Just watch a couple of episodes of Supernanny at least before you decide to add one more destructive, disturbed sociopath into the mix of masses of planet-, and animal-torturing demonic sh1theads.

Sheesh.. you can't trust ANYONE or any youtube channel to be intelligent or produce content that passes the BARE MINIMUM..

How can anyone have any hope or happiness in this kind of a world? How??