Doryoku Suki no Tensai Renkinjutsushi

A man dies without having accomplished anything, despite his conviction of being talented. He is reborn in another world as Isaac, the son of a family of modest alchemists. Determined not to ruin this second life, he trains from childhood by learning the language, cultivating his magic and mastering alchemy. Surrounded by a loving family, his peaceful life changes when a mage from the city and a mysterious stupid girl spot her potential... https://www.cmoa.jp/title/358771/