Benjamin Franklin is the likely inventor.
Most likely Anton Van Leeuwenhoek, inventor of the microscope
Eli Whitney was likely the inventor who solidified the practice of slavery in the South. His invention of the cotton gin made cotton monstrously profitable.
It is difficult to pinpoint the first inventor on Earth as innovation has likely existed for as long as humans have. However, some early inventors known in history include Archimedes, Leonardo da Vinci, and Thomas Edison.
I do not think this can be determined as it is so ancient and there are so many types, each likely independently invented.
That would most likely be the inventor of Levi Jeans, Levi Strauss.
The exact inventor of soap is unknown, but the earliest recorded use of soap dates back to ancient Babylon around 2800 BCE. It was likely discovered by early civilizations who noticed the cleaning properties of mixing animal fats with wood ash.
Like other early computer inventions, there is no single inventor of the motherboard. The early computers each had their own version of a motherboard.
The iron horseshoe was made during the Middle ages (also called the Medieval times), likely the inventor was somewhere in Europe or England as these were the places most likely to have professional iron workers.
The inventor of fire is not known as fire was likely discovered by early humans through natural events such as lightning strikes or volcanic eruptions. The controlled use of fire for cooking and warmth is believed to have been developed by early hominids over millions of years.
Fiona Wood is a plastic surgeon, though she did invent spray-on skin for burns victims. Most likely she would be called an inventor.
Charles Babbage is commonly credited with the invention of the programmable computer, while Ada Lovelace is commonly credited as the inventor of the first computer programming language (called "Ada" after the inventor). Depending on the precise meaning of your question, either one of these two people are likely whom you are looking for.