No - 1500 is the total number of Palestinians killed - not 1500 children. Make sure your facts are correct before banding about the first number you see.
No, Tinmore is right - the number is the number of children. The title of the link is "Remember these children" - one would assume that the number represents children, not all Palestinians.
But, if still in doubt, here's another source:
Statistics | B'Tselem
I don't think it's Tinmore that needs to check his facts.
A lot of children have been killed or suffered horrendous injuries on both sides, as this incident shows, but in terms of numbers many more Palestinian children have been killed or injured.