The barrier (class 1) from the Stealing Creation minigame is made by using a class 1 of sacred clay on a creation kiln. It is the weakest and lowest-levelled barrier. Its purpose is to keep members of the opposing team from accessing a resource that your team is gathering. The barrier will create a wall around the chosen resource spot with portals colour coded to the team that created it. Only members of the team that set up the barrier can pass through it. A barrier may be removed by the other team by attacking the barrier over time, weakening it until it is destroyed . A class 1 barrier requires level 1 Construction to make and place at resource banks. The barrier may be repaired by placing barriers that are level 1 or higher on the same resource. If a player happens to die, they will be spawned within the nearest barrier controlled by their team, or inside their team's base.
Although it's the weakest barrier, the class 1 barrier keeps the enemy team from getting to whatever you placed it around for a short while. There are several reasons that you might wish to keep the other team out. One reason might be to protect the low-level skillers from being attacked. Another reason could be to keep the other team from stealing your team's higher level of clay. You may also wish to build the barrier around a creation kiln so the other team may not use it.
However, in many cases this might be more of a hindrance than help. The enemy team could usually take class 1 barriers down with a few hits and walled plots are often a beacon to PKers. It also slows down resource transport between the plot and kilns.