What is the ruling on working for a recruitment company that supplies employees to alcohol companies, banks, and insurance companies, and would I be sinful if I were to recruit people for these places?

It is not permissible to work in interest-based banks, insurance companies, or wineries, nor is it permissible to assist them in any way, including directing workers to them. This is in accordance with the Almighty's saying: (And cooperate in righteousness and piety, but do not cooperate in sin and aggression), and the Prophet, peace and blessings be upon him, said: (Whoever calls to misguidance will bear a sin similar to the sins of those who follow him). This applies to both Muslims and non-Muslims, as disbelievers are addressed by the branches of Sharia. Therefore, job seekers must be guided to permissible activities, and if that is not possible, one must switch to another permissible job.