Basically in simple terms, think you're playing the lotto and buy one ticket. You have a chance of winning with just one ticket, but your odds are very low, and they increase if you play with more tickets. (the big mining pools and farms are playing with millions of tickets).

Now think if they pull the winning numbers first, and we need to buy random tickets looking for the right combination of numbers before anybody else does. Your one ticket hits 1 number, not enough to win, but that is your best ticket, now you buy another, and you hit 3 numbers, this is still not enough to win, but this is your new best. Every new block @10 mins is a new lotto drawing, your old best number from another block means nothing toward the new block other than a way to show how close you came. The lower your hash rate is like only buying a ticket maybe once a day or month compared to the mega farms/pool buying millions of tickets every 10 minutes or for every block.