How important is it to give training lower level worker, eg, laborer, helper, beginners sales people etc?

Thanks to invite.

Training is a very useful tool to promote a helathy professional culture at all levels.

I would prefer using another word rather than lower level. Blue collars will elaborate your meaning. Anyways for employees and colleagues working in the tasks you mentioned, it will be more beneficial to give them incentives and business bonuses and making them feel more secured in their jobs as this will be impacting very much on their productivity and loyalty as well.

There are many objectives of training employees but the major objective is to equip them with the relevant & necessary knowledge, skills & competencies and consequently to update them on the current & possible future trends in their workline.

Its very important to train your entire team to achieve a common goal of organization.