Who is the real developer of dota and what is IceFrogs role? Get your answers here
Before Warcraft 3 there was Starcraft. In Starcraft there was a type of custom map called Aeon of Strife (AOS) which had opposing teams trying to help their team win an ongoing battle in 1-3 lanes depending on the map
When Warcraft 3 came out, these kinds of maps were also made here. Some people started using a design where one base would be in bottom left corner and the other would be in the top right corner and 3 lanes would connect the bases. This model was called Defence of the Ancients since it pitted the Ancients of the Night elf against the Scourge. What was special about the Warcraft 3 version was that instead of just units we now had heroes who could advance in levels, get new skills and even items.
Several versions were made of these (dota night falls and dota outland just to name a few) and one of the most successful was made by a guy who called himself Eul (along with other people like Syllable and so forth)
When the expansion, The Frozen Throne, came, a guy who called himself Guinsoo, appeared. He copied the game to the new expansion and copied all the most powerful heroes from all the old versions of dota into his new game - Dota Allstars. Needless to say it was horribly imbalanced and never worth competitive playing but it was fun none the less.
After some time, version 5.84 came out and Guinsoo disappeared. Icefrog decided to take up where Guinsoo left off. He picked up the dota developing and with him came a new era where balance and professionalism was in the high seat and he made dota what it has become today - a thriving game with loads of competitive matches, giant leagues and an utterly amazing user base.
Many people regard Icefrog as the father of dota because they see it as if he took a rough sketch and made it actually playable and balanced; he may not be the original dev but he is the best dev in dota history
Disclaimer: for the sake of the TL;DR people I only included the most central stuff - there is a lot of stuff which has been simplified or left out for the sake of the readability. Also, didn't proofread since im tired and need sleep bad