who is the first son of lord shiva

According to Hindu folklore, Lord Shiva had two sons: Ganesha (also known as Vinayaka) and Kartikeya (also known as Skanda, Murugan, or Subramanya).     According to popular belief, Lord Shiva and Goddess Parvati had their first child, Kartikeya. They were supposedly developed by Lord Shiva and the divine fire Agni to extinguish the demonic Tarakasur.
    As the god of battle and triumph, Kartikeya is frequently seen riding a peacock and brandishing a spear.     On the other side, Lord Shiva is not involved when Goddess Parvati invokes Ganesha. He is revered before the start of each new endeavour or auspicious occasion since he is known as the remover of impediments. Ganesh is frequently pictured as having an elephant-like head and a bulky human torso.