eBay is not an online store. It's a kind of billboard on which anyone can sells items. Each seller sells their own items.
If you bought multiples items from different sellers, they will be shipped separately since sellers from all around the world are on eBay.
Shipping delays depends on multiples factors such as : delivery method, shipping carrier, customs clearance delays, weather condition, country of origin, etc. Items bought from Asia may take up to one month or more if it's shipped by regular mail "economy"