system
Given the following post, respond as if you're commenting on Reddit:
human
[Doctor Who] Weeping Angels episode - How come 51th century soldiers using late 20th century armor and weapons?

Also how come humans never develop weapons that can actually deal damage to daleks/cybermen/aliens, don't they understand how useless projectile weapons are?

EDIT: 51st century* I'm dumb.
gpt
The humans in the 20th century kit?  It's a classic look.  Have you seen the Swiss Guards who stand guard over the Vatican?  Same deal.

Humans and weapons against Daleks:  
Humans do.  You have to understand that the Daleks also improve their defensive systems and - just prior to the start of the Time War - they pulled off something no one else had managed.  The Daleks raided Goth.  

Goth was one of those worlds that made a name for itself because the population was very good at one thing.  In this case, that one thing was making weapons and defensive systems.  But mostly weapons.  The people who lived on Goth were known as The Deathsmiths.  Even the farmers.  It was that sort of planet.  

Sadly, the Deathsmiths over-reached themselves and created a weapon so powerful that it wiped them - and anyone else who went to Goth (including Sontarans and Cybermen) - out.  In a lot of ways, the final weapon the Deathsmiths created was a lot like The Moment, only much less friendly.

The details of the Dalek raid on Goth are lost, but we do know they got away with the Deathsmith's finest creations.  This is why the Time War Daleks can go toe to toe with the Time Lords, and why they are extremely hard to stop.

Prior to that, humans from the 1960s took out Daleks with anti-tank weapons and one of the Doctor's companions killed one with a baseball bat.

Additionally, UNIT are known to have adapted their arsenal.  At one point, the Brigadier tells the Doctor they now have armour piercing rounds for Daleks and gold rounds to take out Cybermen.  The Doctor asks if they have any silver bullets.  It turns out they do.