While Blizzard never released any development tools for Warcraft besides the unit stats editor, a certain BJ Pollard reverse-engineered the map format and in 1995 wrote and made public an editor that allowed to create user maps for the game. These would be loaded a simple saved game files and distributed as such.

There were quite a few levels created with this tool, albeit not as many as Warcraft II PUDs. Some were even published on several PC Gamer coverdisks alongside Doom WADs and other user-created content. However now these levels are very hard to find. By digging the Internet Archive's Wayback Machine, I was able to find a webpage from the late 90s which contains a large selection of the maps, including those found on PC Gamer disks:
http://web.archive.org/web/19990117000154/http://www.geocities.com/Colosseum/1334/warcraft.html

As far as I can tell, this is the most complete collection of the files with intact downloads. A few more can be found here (alongside duplicates from the first page repacked in ARJ):
http://web.archive.org/web/19990503093125/http://members.aol.com/heiska/ewc1.html

There are also four scenarios by Kenny Chong:
http://www.oocities.org/tokyo/2077/warcraft.html

Several more are mentioned on this page but sadly the downloads were not preserved by the Wayback Machine:
[url=http://web.archive.org/web/19980212142057/http://panesu.esu14.k12.ne.us/~dpelster/game/levels.html]http://web.archive.org/web/19980212142057/http://panesu.esu14.k12.ne.us/~dpelster/game/levels.html[/url]

NOTE: The URL parser here seems to have trouble with Wayback Machine links so please copy them and paste in your browser's address line manually.

I did it also
https://m.youtube.com/watch?v=NTfJ9TW9i_Q&t=7s

Is it available for download anywhere?

Did you use the same editor by BJ Pollard?

Yes I can share it, I will edit all missions but need time, I have allready edited but few missions doesnt work with gog warcraft1, you can check rest missions in my YouTube channel

No I didnt, I used wardraft to open data and hex editor

Ok I edit 1-3 orc 1-4 human

https://ufile.io/gwj33a6w

THIS WORK ONLY WITH GOG EDITION ( didnt test with diffrent)

be sure and copy orginal data.war! replace with new, start game
GL HF

The link has expired for free access. Would you please re-upload it? Thank you! I didn't see any downloads in any of these links,just expired or "not found" web pages.

I agree, All three seem to be more click bait or downright nasty suspect sites. Perhaps if there is a moderator, they could double check and if so delete message and mebership. If I find any I'll let you know.

Apologies, it seems that the HTML parser in these forums simply ignores the web.archive.org part of the link, hence you get forwarded to nonexistent pages. I did not know that when posting. Just copy the entire link with the http://web.archive.org/ part and paste in the URL field of your browser, or follow the same links from here:
https://www.vogons.org/viewtopic.php?t=66499