Definitely a wart. They are very contagious which is why you saw it jump from one finger to the adjacent finger. Please take care during an outbreak not to pop them (which will cause it to spread) or touch your face or other body parts. It is caused by a viral infection (papillomavirus : HPV) You may have gotten it by shaking hands with someone, or on a grocery cart or shared keyboard. The virus invades the outer layer of skin, usually through a tiny scratch or cut, it causes rapid growth of cells on the outer layer of skin – creating the wart. Also it attacks if your immune system is weak. 1. wash your hands thoroughly and regularly 2. use those wipes on the grocery cart before you use it 3. if you go to the gym before you workout with equipment someone else sweat on who might have the virus wipe it off.
This is common remember that warts can spread quickly and as soon as you see an outbreak you should act immediately. Try trying at home treatments salicylic acid or clear nail polish or tape or any other method that suffocates the virus. If that is not working for you see a dermatologist, they can freeze or burn the wart off, and you might ask your doctor for an immune boosting medicine.