Why am I getting an ‘Incorrect attribute value type’ error when I try to run this in Terraform?

Terraform
1

I am trying to create a lambda for each stage in my stages variable then pass in the arn of each role from my lambda_iam_role to each corresponding lambda, when I try applying it I get this, Could someone explain why please?

│ Error: Incorrect attribute value type
│ 
│   on modules/lambda/lambda.tf line 20, in resource "aws_lambda_function" "lambda_function":
│   20:  role          = var.lambda_role_arn
│     ├────────────────
│     │ var.lambda_role_arn is a list of string
│ 
│ Inappropriate value for attribute
│ "role": string required.

Below is my configuration

iam.tf

variable stages {
  type        = list(string)
}

variable lambda_iam_role {
  type = list(string)
}

data aws_iam_role lambda_iam_role {
  for_each = { for names, stage in var.stages : stage => names }
  name     = element(var.lambda_iam_role, each.value)
}

output lambda_role_arn {
  value = {
    for stage, role_arn in data.aws_iam_role.lambda_iam_role :
    stage =>{
    role_name = role_arn.name
    role_arn  = role_arn.arn
  }
  }
}

Lambda.tf

variable stages {
  type        = list(string)
}


variable lambda_role_arn {
  type        = list(string)
  description = "The ARN for the lambda IAM role"
}

resource aws_lambda_function lambda_function {
  filename      = local.lambda_zip_location
  for_each = { for stage in var.stages : stage => "${stage}_data_lambda" }
  function_name = each.value
  handler       = "index.lambda_handler"
  role          = var.lambda_role_arn

  source_code_hash = data.archive_file.lambda-zip.output_base64sha256

  runtime       = "python3.9"
  timeout       = "90"

}

Main.tf

variable stages {
  type        = list(string)
  default = "['a','b','c']
}

variable lambda_iam_role {
  type = list(string)
  default = "['login_role','logout_role','support_role']"
}


variable lambda_role_arn {
  type        = list(string)
  description = "The ARN for the lambda IAM role"
}

module iam {
  source              = "./modules/iam"
  environment         = var.environment
  stages              = var.stages
  lambda_iam_role     = var.lambda_iam_role
}

module lambda{
  source                       = "./modules/lambda"
  lambda_iam_role    = module.iam.lambda_role_arn
  aws_region               = var.aws_region
}
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