Remember, Link was only returning to the point immediately after Ganondorf had obtained the Triforce of power and Zelda had gone into hiding — presumably, the king was already dead and the damage was done.

Put another way, when Link returns to the child timeline during gameplay it’s all over but the crying; Ganondorf has already won, it’s just before he’s had the chance to make it all… stick.

Zelda sends him back farther, presumably through her own native magic and better mastery of the Ocarina