For the purpose of promoting the public health, safety, morals, comfort, and general welfare, conserving the value of property throughout the community, and lessening or avoiding congestion in the public streets and highways, the Legislative Body may, from time to time, in the manner hereinafter set forth, amend the regulations imposed in the districts created by this Ordinance or amend district boundary lines, provided that in all amendatory Ordinances adopted under the authority of this section, due allowance shall be made for existing conditions, the conservation of property values, the direction of building development to the best advantage of the entire community, and the uses to which property is devoted at the time of the adoption of such amendatory Ordinance.